Table 4. Predictive accuracy of models including the AJCC 7th edition pN staging system and the modified N staging system.

Stage	P-valuea	HR (95% CI)a	LRa	AIC	C-index	Bootstrap C-index
AJCC 7th edition of pN staging	0.001	3.052 (1.626–5.726)	14.148	130.14	0.698	0.699
Modified pN staging	<0.001	3.335 (1.889–5.886)	21.325	122.55	0.745	0.742

Abbreviations: AIC=Akaike information criterion, C-index=concordance index, LR=likelihood ratio.

^aLogistic.